Duo carb DCOE 40 conversion 1502

[APka]

Hello everyone ! 

 

After hesitating for a while as to which path i should take for my 76 1502, I have decided to keep it with it's original engine, but to simply modify the carb. From what I have read, most people prefer the Weber DCOE, over other types, (even stock?). As such, I plan to possibly go from a Single stock 1502 carb --> Duo Weber DCOE 40, and possibly a new exhaust line.

 

Now I have been reading up on the DCOE, but I am still unsure on a few points, and this is why I come to you for any expertise possible, it will all be very much appreciated!

 

My first question is : Is a Weber DCOE 40, a Weber DCOE 40. Let me explain, are they a single model that fit all cars that simply require a specificly suited manifold? Or are there different models of DCOE 40 that exist?

[TobyB]

There are different variants, indicated by the number after the 40, as in DCOE40-154.  It's stamped into the cover, and indicates what progression drillings the carb has.

 

As to what you'd want for a 1600, that's beyond my expertise.  Try searching DCOE Progression on this site...

 

t

 

[APka]

5 minutes ago, TobyB said:

There are different variants, indicated by the number after the 40, as in DCOE40-154.  It's stamped into the cover, and indicates what progression drillings the carb has.

 

As to what you'd want for a 1600, that's beyond my expertise.  Try searching DCOE Progression on this site...

 

t

 

Thanks, that's already a good start for me !

[Simeon]

You will definitely want some small chokes in them. 32mm or of that order. You also need to seek out the 1600 sized inlet manifolds. You can physically mount them using the 2000 sized manifolds but you will struggle to tune them. 

 

It's all workable. You just need to look at the old Italian cars fitted with them and sized from 1300 to 1800. 

[williamggruff]

As Toby notes, there are many variants of DCOE 40s. Some of them were developed specifically for 1500-1600cc motors. Some of those were developed for motors that rev higher than your stock 1500cc M10. The volume of air through the carb, and the vacuum signal from the motor that pulls air through the carb, play significant roles in how well the carb feeds the motor throughout the rev range. You might learn that you don't want DCOE 40s, but DCOE 38s. 

 

There are several great books on tuning Weber DCOEs. Three of my favorites are:

 

"How to build & power tune Weber and Dellorto DCOE and DHLA carburetor" by Des Hammill;

 

"Weber carburettors tuning tips and techniques" by John Passini; and 

 

"Weber Carburetors" by Pat Braden.

 

All are valuable resources, and each will present you with critically important insights into how to select, jet and tune DCOEs.

 

Other resources to consider include:

 

Pierce Manifolds--a purveyor of Weber carbs and parts. They may be able to recommend one or more DCOE bodies to look for. 

 

eBay merchant alfa1750--sells Weber and Dellorto parts. Based in Italy, and seems to have broad knowledge of, and access to DCOE bodies and parts. 

Edited May 18, 2017 by williamggruff

[APka]

3 minutes ago, williamggruff said:

As Toby notes, there are many variants of DCOE 40s. Some of them were developed specifically for 1500-1600cc motors. Some of those were developed for motors that rev higher than your stock 1500cc M10. The volume of air through the carb, and the vacuum signal from the motor that pulls air through the carb, play significant roles in how well the carb feeds the motor throughout the rev range. You might learn that you don't want DCOE 40s, but DCOE 38s. 

 

There are several great books on tuning Weber DCOEs. Three of my favorites are:

 

"How to build & power tune Weber and Dellorto DCOE and DHLA carburetor" by Des Hammill;

 

"Weber carburettors tuning tips and techniques" by John Passini; and 

 

"Weber Carburetors" by Pat Braden.

 

All are valuable resources, and each will present you with critically important insights into how to select, jet and tune DCOEs.

 

Other resources to consider include:

 

Pierce Manifolds--a purveyor of Weber carbs and parts. They may be able to recommend one or more DCOE bodies to look for. 

 

eBay merchant alfa1750--sells Weber and Dellorto parts. Based in Italy, and seems to have broad knowledge of, and access to DCOE bodies and parts. 

I have the "Weber Carburetors" by Pat Braden in front of me as I type this, yet this topic was not really reviwed. Also, I have never found any information even showing the existance of a DCOE 38?

 

[Oldtimerfahrer]

Not to rain on your parade, but you won't get more than 5 or 6 hp out of that setup at a significant cost. It will look nice, if you take the filters off you might notice some additional intake sound but not a lot. Your money might be better invested by retrofitting the engine up to 1602 spec (8.6:1 compression) with 1602 carbs which would give you 85hp. The low compression engine (8:1) in the 1502 is not a good basis for larger carbs so you won't even reach the performance of a stock 1602. Might actually be less driveable and consume more fuel. 

Regards,

Andrew

[TobyB]

This might help, tho...

 

t

[Swiss 2002Tii]

APka, I haven't seen it mentioned here, so I'll toss this out there... I recall that on my '68 1600 and then later on my '70 2002 that when I wanted to convert from the old single downdraft Solex to a dual downdraft Weber (and I think it was a DCOE 38) I first had to find a newer intake manifold with a 4-bolt mount instead of the original 3-bolt mount used with the Solex.

Sound familiar to anyone?

Tom

[arminyack]

For a 1502 to use a 32/36, you need the manifold off a euro model 316 e21, carbed car. Those ones have the smaller intake ports to match your head

Edited May 18, 2017 by arminyack

[Drosselhebel]

The euro E12 518 also had the small-port two barrel manifold.

[APka]

Maybe I would be better off with just a single DCOE 38 or 40? as opposed to dual?